1296746 - CompositorWidgetParent doesn't honor MOZ_MUST_USE on IPDL send methods

Status: RESOLVED FIXED

(Core :: Widget: Win32, defect)

Description

[Nathan Froyd [:froydnj]]

clang-cl complains thusly:

11:30.66 c:/m-c/widget/windows/CompositorWidgetParent.cpp(59,5):  warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
11:30.66     SendObserveVsync();
11:30.66     ^~~~~~~~~~~~~~~~
11:30.66 c:/m-c/widget/windows/CompositorWidgetParent.cpp(61,5):  warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
11:30.66     SendUnobserveVsync();
11:30.66     ^~~~~~~~~~~~~~~~~~

Comment 1

[Nicholas Nethercote [inactive]]

Why does this manifest as a warning instead of an error?

Comment 2

[Nathan Froyd [:froydnj]]

(In reply to Nicholas Nethercote [:njn] from comment #1)
> Why does this manifest as a warning instead of an error?

This is Windows-only code, which means that as MSVC doesn't define anything useful for MOZ_MUST_USE, the problem goes undetected in our normal builds.  The warning comes from clang-cl, and would be a hard error in --enable-warnings-as-errors builds, which I was not doing.

Comment 3

[Nicholas Nethercote [inactive]]

> This is Windows-only code

Makes sense. One more reason to get clang-cl builds up and running! :)

Comment 4

[Nathan Froyd [:froydnj]]

Attachment: explicitly ignore the result of Send{Observe,Unobserve}Vsync in CompositorWidgetParent

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/e95f8d487fbc
explicitly ignore the result of Send{Observe,Unobserve}Vsync in CompositorWidgetParent; r=jimm

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/d43cca3b50a7
followup - fix silly typo; r=bustage

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/e95f8d487fbc
https://hg.mozilla.org/mozilla-central/rev/d43cca3b50a7